Needle-free hypodermic jet injection has been known in the past. In jet injection devices, either springs, electric drivers, or pressurized gas is often used to drive a plunger. The plunger, in turn, advances within an ampule causing liquid medication to be ejected with sufficient velocity to penetrate the skin of a patient. Prior to operation, the ampules must be filled with medication. Usually a filling needle attached to the ampule is used to draw medication from a standard medication vial into the ampule. Thus, it has long been recognized that a pre-filled ampule for jet injection is advantageous due to its ease of use, convenience, and improved control over medication administration. However, sale of a pre-filled ampule would require costly and time consuming regulatory approval.
Most medications for injection are currently packaged in glass containers with rubber or elastomeric closures on one or both ends. The glass, primarily, lacks the strength required to withstand the stresses of jet injection, thus making the glass medication vials unsuitable for use in jet injection. Furthermore, adequate mechanical support for the common glass medication vial, to prevent its breakage during jet injection, has yet to be developed. In addition to the strength problem of the glass, the elastomeric closures or plugs are not designed to withstand the pressure levels required for jet injection. Moreover, it would be relatively expensive and time consuming to modify, for jet injection, the medication vials that are currently in use. Modification would require extensive development, testing, and regulatory approvals.
Therefore, it would be desirable to have a device that efficiently and conveniently transfers medication from the glass medication vials, that are currently in use, to the ampules used in jet injection, and, to have a device that improves control over medication administration, maintains a sterile medication environment, is easy to use, and is relatively inexpensive and easy to produce.